In order for polycrystalline solar cells to be cost-effective for terrestrial applications, their cell efficiency must be considerably increased from its present values. This is especially true for thin film solar cells. It is known that the efficiency of polycrystalline solar cells is severely impaired by the presence of the grain boundaries and their influence on carrier recombination.
One category of previous attempts to diminish their influence has focused on their passivation through the positioning of atoms (hydrogen, phosphorous, etc.) that are expected to tie up the dangling bonds at the interface states located at the grain boundaries. Another method reduces the importance of these grain boundaries losses by making grain sizes much larger than the minority carrier diffusion length; but this approach may imply high material cost.